How Did Preemption Affect Migration

How did preemption affect migration?

A) More people migrated when assured that preemption would allow them to own the land they had improved.
B) It allowed Native Americans the right to refuse to leave land they had improved in Florida to settle in the West.
C) It gave land speculators the first rights to purchase public domain land, encouraging speculators to migrate west.
D) It allowed the government to seize land from farmers, discouraging people from moving west.
E) It permitted squatters to occupy Native American camps while they were migrating for seasonal hunting or gathering trips.